Electrode insulator



April 2, 1957 W. w. wATRous, JR '2,787,722

ELECTRQDE INSULATOR Filed sept'. 16, 1955v j \\\\\\\\\\\\\\\\m\\\\\\\\\\\\\w s /ll I l\\\\\ I I I Il',lll',l'111111111111111llylllllllllz v a f l f f r f f f l n u f f f f f f f f f r f f f WARD w. wArRous, JR.

' I NVEN'TORv ATTORNEY ELECTRODE INSULATOR Ward W. Watrous, Jr., Chatham, N. J., assignor to Chatham Electronics, Division of Gera Corporation, a corporation of New Jersey Application September 16, 1955, Serial No. 534,702

1 Claim. (Cl. 313-199) This invention relates to an electrode insulator for use in gaseous discharge devices. It has particular reference to a structure for insulating and retaining two electrodes within a discharge device which may be subjected to dierences of potential which may range up to 10,000 volts.

Many forms of insulators have been used in electron and gaseous discharge devices. In their simplest form these insulators comprise mica washers, mica plates riveted to other electrodes, or to supporting members, and various forms of ceramic blocks. vSuch prior insulators must generally be assembled and secured to their components before the electrode structure is mounted within the glass envelope. There are frequent occasions, however, when assembly must be made after one or more electrodes have been mounted within the envelope or have otherwise been assembled so as to make the usual assembly quite difficult. The present insulator design permits assembly within an electrode enclosure in a manner which would be exceedingly difficult to perform with the known types of insulators. The insulator further is designed with a shield so as to make sure that gaseous ionization between adjacent electrodes is impossible.`

One of the objects of this invention is to provide an improved electrode insulator which avoids one or more of the disadvantages and limitations of prior art arrangements.

Another object of the invention is to permit assembly of one electrode within another electrode without recourse to the usual fastening means.

Another object of the invention is to simplify and improve the construction of electrode assemblies.

Another object of the invention is to provide an electrode insulator which will permit relative movements of two electrodes subjected to unequal heating and cooling cycles.`

Another object of the invention is to provide an electrode insulator which is shielded against electrostatic tields which might cause gaseous ionization and current ow.

Another object of the invention is to shield all the junctions between insulator material and conductive shields from electric elds so that there is no tendency for a cathode spot to form.

The invention comprises an electrode insulator for slidably mounting two electrodes within the envelope of a gaseous discharge device which contains gas at a reduced pressure and comprises a cylindrical conducting shield which is closed at vone end and is secured topa tirst electrode. A cylindrical insulator is mounted within the shield and is formed with an axial opening. A conducting rod is secured to a second electrode and is adapted to lit into the axial opening. The conducting structures which support the cylindrical shield and the conducting rod are separated by a distance which is less than the mean free path of electrons at the reduced pressure.

For a better understanding of the present invention,

nited States arent 'ice together with other and further objects thereof, reference is made to the following description taken in connection with the accompanying drawings.

Fig. 1 is a cross sectional view of a gaseous discharge device showing a portion of the envelope and three electrode insulators mounted between two electrodes.

Fig. 2 is a cross sectional View of the discharge device shown in Fig. 1, taken along line 2--2 of that figure.

Referring now to the drawing, an envelope 10 surrounds all the electrodes Iand contains gas at a reduced pressure. A cylindrical electrode 11 is secured within the envelope and supports a control electrode 12 and a baffle plate 13. lust above the control electrode is an anode 15 which is connected to a positive source of positive potential and is one terminal for the discharge which passes through the tube. The control electrode 12 and the bale 13 are both conductively joined to the cylindrical electrode 11. A baffle plate 14 is joined to a second cylindrical electrode 16 which is generally connected lto a cathode (not shown) and may be connected to ground by means of an external connection.

The electrode insulator is shielded by a cylindrical shield 17 which is closed at its bottom end and connected to baffle plate 14 by a Iflange 1S. An insulator 20 is mounted within shield 17 and completely fills the space enclosed by the shield except for an axial opening 21 and a slight chamfer 22 at the open end of the shield. A hole 23 is provided in baile plate 14 in general alignment with opening 21.

The second electrode 13, which in this case is a bathe plate connected to the control electrode 12, is provided with a plurality of conducting rods 24, permanently secured to plate 13 and adapted to tit into the/central openings 21 in insulators 20. Rods 24 are long enough to make contact with a major portion of the insulator material but do not extend to the bottom of the opening 21 so that sufticient leaway is provided to permit relative motion between any of the rods and the insulators in which they are positioned due to expansion and contraction of the various metallic electrode materials associated with bathe plates 14 and 13.

lIt should be noted that cylinders 11 and 16 are spaced at a distance which may be small in relation to the mean free path of electrons in the gas at the reduced pressure in the envelope. lt is also evident that bathe plates 13 and 14 are within the same distance and nowhere within the geometry of the insulator is there suicient length for an electron to cause ionization which will result in an arc or glow discharge. Shield 17 effectively shields the rod 24 from any electrostatic iield which might be present due to other electrodes placed within the walls of cylinder 16. The hole 21 may, under some conditions, eXtend through the entire insulator 20.

When the parts are assembled, cylinder 11 is first se cured within the envelope in proper spaced relation to the anode 15 and anchored by means not shown in the drawings. Then cylinder 16 is pushed into cylinder 11 and adjusted so that rods 24 t into openings 21. After being adjusted for proper spacing between plates 13 and 14, the lower portion of cylinder 16 is anchored, and the tube is ready to be finished and exhausted.

While there have been described and illustrated specilic embodiments of the electrode insulator, it will be obvious that various changes and modications in the materials and in the relative dimensions can 4be made therein without departing from the field of the invention which should be limited only by the scope of the appended claim.

l claim:

An electrode insulator for slidably mounting two e1ectrodes within the envelope of a gaseous discharge tube 3 4 which? contains gas atrafreduced pressureV comprising,` a References "Cited in the leof this patent cylindrical conductingshield closed at one end and se- UNITED STATESV PATENTS cured to a rst electrode, an insulator mounted within said shield and having a central axial opening, a con- Re15585' Sauerelsen Apr' 24 1923 ducting rod secured toa second electrode-and Vfitting-into 5 2518879 Germeshausen Aug' 15 1950 said amialopcning,` andconducting-structures connected 216441101 Watrous June 30 1953 to said rst and second electrodes which ,are separated bya distance` whichis less than the mean free=patl1-`of electrons at said reduced pressure.- 

